A flow path of cooling water of a water jacket sometimes has to be provided so as to penetrate a chain chamber because of a layout structure of an engine and a radiator of an automobile engine (for example, referring to Patent Literatures 1 to 3). When the flow path of the water jacket penetrates the chain chamber, a chain case is provided with a flow pipe line connected to a flow pipe of the radiator. When the chain case is attached to a cylinder block or a cylinder head by fastening with bolts, the flow pipe line of the chain case communicates with a flow port of the water jacket. Thus, the flow path communicating the flow port with the flow path line is provided. A joined portion of the flow port and the flow pipe line is positioned in the chain chamber and is provided with a seal member such as an O-ring or a gasket so as to prevent cooling water from leaking to the chain chamber from the flow path and to prevent oil from flowing into the flow path from the chain chamber.
Patent Literature 1 discloses that a liquid gasket is provided for the joined portion. Patent Literature 2 discloses that two O-rings are concentrically provided for the joined portion, an inner O-ring is used for preventing leakage of cooling water and an outer O-ring is used for preventing leakage of oil. Patent Literature 3 discloses that a sheet-like seal member having an inner water-proof seal portion and an outer oil seal portion is provided for the joined portion. These embodiments prevent leakage of cooling water into the chain chamber and flowing of oil into the flow path at the joined portion in the chain chamber. Patent Literature 4 discloses a gasket provided for a joined face of a connection portion of gas piping, not for an automobile engine, the gasket comprising a sheet-like gasket at an inner circumference and a sheet-like gasket at an outer circumference.